It is unclear whether circulating antibody levels conferred protection against SARS-CoV-2 infection among patients receiving dialysis during the Omicron-dominant period.

We followed monthly semiquantitative SARS-CoV-2 RBD IgG index values in a randomly selected nationwide cohort of patients receiving dialysis and ascertained SARS-CoV-2 infection during the Omicron-dominant period of December 25, 2021 to January 31, 2022 using electronic health records. We estimated the relative risk for documented SARS-CoV-2 infection by vaccination status and by circulating RBD IgG using a log-binomial model accounting for age, sex, and prior COVID-19.

Among 3576 patients receiving dialysis, 901 (25%) received a third mRNA vaccine dose as of December 24, 2021. Early antibody responses to third doses were robust (median peak index IgG value at assay limit of 150). During the Omicron-dominant period, SARS-CoV-2 infection was documented in 340 (7%) patients. Risk for infection was higher among patients without vaccination and with one to two doses (RR, 2.1; 95% CI, 1.6 to 2.8, and RR, 1.3; 95% CI, 1.0 to 1.8 versus three doses, respectively). Irrespective of the number of vaccine doses, risk for infection was higher among patients with circulating RBD IgG <23 (506 BAU/ml) (RR range, 2.1 to 3.2, 95% CI, 1.3 to 3.4 and 95% CI, 2.2 to 4.5, respectively) compared with RBD IgG ≥23.

Among patients receiving dialysis, a third mRNA vaccine dose enhanced protection against SARS-CoV-2 infection during the Omicron-dominant period, but a low circulating RBD antibody response was associated with risk for infection independent of the number of vaccine doses. Measuring circulating antibody levels in this high-risk group could inform optimal timing of vaccination and other measures to reduce risk of SARS-CoV-2 infection.

目前尚不清楚在 Omicron 占主导地位期间接受透析的患者中，循环抗体水平是否能提供针对 SARS-CoV-2 感染的保护作用。

我们在 2021 年 12 月 25 日至 2022 年 1 月 31 日 Omicron 占主导地位期间，对随机选择的全国范围内接受透析的患者队列进行每月半定量 SARS-CoV-2 RBD IgG 指数值的跟踪，并使用电子健康确定了 SARS-CoV-2 感染情况记录。我们通过疫苗接种状态和循环 RBD IgG，使用考虑了年龄、性别和既往 COVID-19 的对数二项式模型，估计了记录在案的 SARS-CoV-2 感染的相对风险。

截至 2021 年 12 月 24 日，在 3576 名接受透析的患者中，901 名 (25%) 接受了第三剂 mRNA 疫苗。对第三剂的早期抗体反应强劲（测定限度为 150 时的中位峰值指数 IgG 值）。在 Omicron 占主导地位的时期，有 340 名 (7%) 患者记录了 SARS-CoV-2 感染。未接种疫苗和接种 1 至 2 剂疫苗的患者感染风险较高（分别与接种 3 剂疫苗相比，RR，2.1；95% CI，1.6 至 2.8；RR，1.3；95% CI，1.0 至 1.8）。无论疫苗剂量多少，循环 RBD IgG <23 (506 BAU/ml) 的患者感染风险较高（RR 范围，2.1 至 3.2，95% CI，1.3 至 3.4 和 95% CI，2.2 至 4.5）分别）与 RBD IgG ≥23 相比。

在接受透析的患者中，第三剂 mRNA 疫苗在 Omicron 主导时期增强了对 SARS-CoV-2 感染的保护，但低循环 RBD 抗体反应与感染风险相关，与疫苗剂量的数量无关。测量这一高危人群的循环抗体水平可以为疫苗接种的最佳时机和其他降低 SARS-CoV-2 感染风险的措施提供信息。